Australian Tropical Rainforest Plants - Online edition

Acacia polystachya A.Cunn. ex Benth.

Click/tap on images to enlarge
Flowers [not vouchered]. CC-BY J.L. Dowe
Leaves and fruit. © CSIRO
Fruit and seeds. CC-BY R.L. Jago
Trunk. CC-BY R.L. Jago
Scale bar 10mm. © CSIRO
Cotyledon and 1st leaf stage, epigeal germination. © CSIRO
Cotyledon stage, epigeal germination. © CSIRO
10th leaf stage. © CSIRO

Bentham, G. (1842) The London Journal of Botany 1: 376. Type: Port Bowen, Cunningham, Port Essington, Armstrong; Haggerstons Island, E. Coast (in fruit), Cunningham.

Common name



Dead bark rough and hard to cut.


Leaves green, phyllodineous. Leaf blades about 0.9-17 x 1.6-2.3 cm. A pink or red gland normally visible on the upper side of the leaf blade-petiole junction. Veins longitudinal, anastomosing, usually 2-4 more prominent than the rest, usually running together near the base. Leaf bearing twigs more or less triangular in cross section.


Spikes +/- white, sparse, about 5-8 cm long, on peduncles about 5 mm long. Calyx rather membranous, broad, about 0.7-0.9 mm long, glabrous, lobes fimbriate, about 0.25 mm long. Corolla deeply lobed, glabrous, about 1.5-2 mm long, about 2-2.5 times as long as the calyx. Stamens about 3-4 mm long. Ovary densely pubescent.


Pod +/- flat, usually twisted, curved or coiled to some extent, up to 10 x 0.6-0.8 cm. Seeds black, longitudinally oriented in the pod, about 4.2 x 3 mm. Funicle red or reddish, encircling the seed and thickened to form an aril-like structure beneath the seed.


Cotyledons elliptic, about 4-5 mm long. First leaf pinnate, second leaf bipinnate. By the third or fourth leaf stage: leaves bipinnate, petiole expanded and flattened. At the tenth leaf stage: leaves phyllodineous, linear, glabrous, usually two main veins run from the base to the apex; a gland present on the margin of the leaf blade adjacent to the petiole; stipules very small, visible only with a lens. Seed germination time 9 to 20 days.

Distribution and Ecology

Occurs in CYP, NEQ and CEQ. Altitudinal range from near sea level to 500 m. Grows in monsoon forest and in drier rain forest but this species probably reaches its best development in gallery forests of Cape York Peninsula. Probably also occurs in New Guinea.

Racosperma polystachyum (Benth.) Pedley, Austrobaileya 2(3): 354(1984).
RFK Code
Copyright © CSIRO 2020, all rights reserved.